Instruments, such as endoscopes, are inserted through a person's mouth into the human body in medical procedures. To prevent the patient from biting into the instrument, a bite block airway is used which is generally basically a rigid plastic tube which is positioned in the patient's open mouth. The instrument is then inserted through the bite block airway or other openings therein into the stomach or other areas.
An example of such a bite block airway is found in my U.S. Pat. No. 5,174,284; the entire disclosure of which is incorporated herein by reference.
During such an endoscopic procedure, the patient is often sedated intravenously. Such sedation generally results in reduced breathing by the patient which in turn reduces the oxygen available to the patient. In order to compensate for such oxygen deprivation, it is standard practice in such endoscopic procedures to administer a supply of a supplementary breathable gas or pure oxygen to patients by using a nasal cannula which usually comprises two prongs extending at generally right angles from a manifold portion having an inlet. A flexible tube connects an oxygen source to the inlet of the cannula. In this way, an adequate supply of oxygen is furnished to the patient.
In the prior art, during such procedures, nasal cannulas were held in place in different ways. Sometimes, the cannulas were taped into place on the patient's face with adhesive tape. Other times, the flexible tube providing the oxygen supply was draped over the patient's ears, as shown for instance in U.S. Pat. No. 3,802,431. Still another alternative was to use a headband attached to the cannula. The band went around the back of the head. In still other instances, the nasal cannula was integrally formed into a face mask as seen in U.S. Pat. No. 4,263,908.
In a more recent development, a standard type plastic endoscopic bite block airway has nasal tunnels formed integrally with the block and extending upwardly to a position below the patient's nostrils whereby an oxygen supply tube could be attached directly to the block with oxygen then being entrained with ambient air and distributed through the tunnels to the nasal passages, or directly into the mouth.
With the nasal cannula separate from the bite block as described above, the taped support or headband support is not totally satisfactory in that the direction of support should be upwards towards the nostrils, whereas the tape and band exert maximum support in a direction inward against the face.
The loops over the ears create an awkward draping of tubes about the patient's head, in the very area where the physician is conducting the procedure on the patient. Again, as with the tape and band, such support is not really firm in the area where support is most needed; namely, right in the area of the nostrils.
Since an integral unit is complex and relatively expensive to mold, it is intended to be reused. Such reuse requires cleaning and sterilization. The integral nasal passages in the form of bores formed into the standard plastic endoscopic bite block have to be vigorously cleaned to prevent contamination and the spreading of infection. Hence, a one-piece cannula and bite block of the prior art had the disadvantage of initial expense and bothersome cleaning and sterilization. Moreover, such integrally molded articles require a compromise between relatively rigid plastics suitable for the bite block and flexible plastic suitable for insertion into the nostrils. Thus, such devices of the prior art required the nasal prongs to terminate below the nostrils due to their relative rigidity.